Decoration of heat-resisting bases, such as glass, earthenware, and china



. it does not require expensive equipment.

Patented Sept. 9, 1952 DECORATION OF HEAT-RESISTING BASES, SUCH AS GLASS, EARTHENWARE, AND

CHINA Frank EnochKerridge and Cyril Stanley Couper,

London, England, assignors to Johnson, Matthey" & Company Limited, London, England, a

British company No Drawing. ApplicationApril19,1948, Serial No. 21,857. In Great Britain April 23, 1947 8 Claims. (01. 106-26 1 Thisinvention relates to improvements in and relating to the decoration of heat-resisting bases, that is to say, bases capableof withstanding firing at a temperature of at least 400 C., such as glass, earthenware and china and is more particularly concerned with the decoration it of such bases with a design or decoration in gold;

,In the art of decorating glass, earthenware, or china with a design in gold, a variety of materials of different composition have heretofore beenused and these have been applied to the ware in a variety of manners.

The materials hitherto used have usually consisted of the following:

1. A product known commercially as liquid gold, consisting essentially of a solution or" a sulphoresinate of gold in suitable solvents;

2. Liquid burnish gold-a suspension of gold powder in essential oils, with or without the addition of liquid gold, and an adhesion promoting material, such as a lead borosilicate flux or a bismuth compound and an extender such as a mercurysalt, and

3. A precipitated gold powder with or without a powdered mercury salt, plus an adhesion promoting agent, also in powder form. 9

In the decoration of articles with a single simple design each of the above materials may be applied by hand painting with subsequent firing, material 3, which is in powder form, being used in a resinous vehicle.

Where a repetitive design is required to, be applied to the ware, however, it is usual to apply the decoration by a printing method.

The methods of printing hitherto generally employed have consisted of (a) applying the design by means of a rubber stamp and firing; (b) engravedplate printing, i. e. applying transiers printed from etched metal or glass plates and then firing; and (c) lithographic printing, i. e. applying lithographic transfers made with a transfer paper either of the collodion slide oii type, or of the stick down type, and then firing. Methods (a) and (b) may be used with any of the materials referred to above, whilst method is generally used only with material 3.

The rubberstamp method of applying a gold decoration is extensively employed owing to the rapidity with which it may be carried out by relatively unskilled operators and the fact that The results obtainable by the use of this method,

however, usually suffer from lack of richness and sharpness of outline; moreover, ceramic colours cannot be printed simultaneously in register with the gold. 1

' the article fired.

- design.

In carrying out the method (b) a transfer is prepared by engraving or etchinga design on a metal or glass plate, filling the interstices or depressions soformed with thegold printing paste, applying a sheet of gummeqtissue: paper, gumrhed'side downwards-to'the coated plate and then removing the paper, which now carries the To decorate an article, the paper is applied, whilst the paste is still moist or sticky with the design-carrying side downwards, to the article. The tissue paper is then soaked oif and This method, in the hands of a skilled operator,

gives a decoration of good quality, but, as the design is applied to the ware in the moist state, it cannot be used for applying both gold and ceramic colour simultaneously in register. A further disadvantage is that transfers prepared by this method cannot normally be stored for future use. l

With lithographic printing, transfers are prepared from a lithographic stone or plate, usually on Duplex type paper, which consists of a paper backing having a gummed sheet of tissue paper on one side thereof. To apply the transfer,

the tissue paper, carrying the design, is stripped off the paper backing and pressed, design downwards, on to the surface of the article to be decorated, the latter having been previously treated with a size of a sticky nature. The tissue paper is then wetted'to softenthegum and allow the tissue paper to be removed, leaving the design adhering to the article, which is then fired; This method enables an article to be decorated with intricate designs in multi-colour, but, as the transfer bears only a very thin depositof enamel or gold, the eifect produced on a transparent base, such as glass, is poor. Better results can be obtained on opaque bases, such ,as earthenware,

china and the like, but the effectiveness of the decoration is detrimentally influenced by the It is also known to decorate wareby applying directly to the article to be decoratedavitreous enamel paste by means of the silk-screen printing method. Such a method of decoration pro- "duces a heavier deposit of enamel than is possible with the lithographic transfer method and designs in multicolours can be readily applied. This method of decoration, however, can in gen eral only be successfully, employed to decorate substantially flat surfaces.

- i The materials referred to above as heretofore used for producing a gold decoration by thevariousmethods outlined are quite unsuited for various reasons for use with the silk-screen printing method and the principal object of this invention is to provide an improved gold paste suitable for direct application to an article to be decorated'by the silk-screen printing method, or for the production, by the silk-screen printing method, of transfers intended for subsequent application to an article.

Another object of the inventionis to provide an improved method of preparing a gold transfer or of decorating a heat-resisting base with a gold design or decoration by which the thickness of the deposit is readily controllable "and tone effects from red-gold to green-gold may be dbtained as desired.

With these and other objects in view, the invention, in its broadest aspect lpro'videsa sil-kr screen printing paste for the preparation or a gold transfer or for direct application to ahe'atresisting base, as hereinbefore defined, said paste comprising a mixture of (1) gold powder, (2)

- mercuricauratepfi-3) a'low fusing fiuxand (4) a ,-medium or'vehi'cle consisting-of a cellulose de- .rivative,'dissolved ina solvent or solvent mixture .having a rate of evaporation suitable for silkscreen printing, in an amount to give the re- .quired viscosity; the proportion oflmedium (4) 'toasolid substances (1, 2 and 3) being preferably substantially l-4 parts-of medium to .2 parts of solids.

Theinvention also provides a "method of preparing a gold transfer which comprises applying to a transferpaper by the silkscreen printing imethoda' paste comprising a mixture 'ofll") gold powder, (-2) rmercuric aurate, -(3) a low fusing flux-and ('4) a medium or vehicle *consisting of .a cellulose derivative, dissolved in a solvent or solvent mixture having a rate of evaporation-suitable-for silk-screen printing-in an amount to give the required viscosity; the proportion of medium '(4) to solid substances (1, 2 and 3) being :preferably substantially 1-4 parts of mediumto 2 parts ofsolids.

The invention further provides fa method of decorating a substantially flat heat-resisting base, as hereinbefore defined, which comprises :applying to the 'base'by the silk-screen printing method a gold printing paste prepared in accord- :ance with the invention, and firing the coated base'at a suitable-temperature to burn away the organic matterand leave 'a firmly adherent coatof-gold 'inthepa'ste'of silver powder or :of "a sil- "ver compound, such as silver carbonate, maybe included in order to give a more greenish tone to the ultimately 'fire'd 'film.

The low fusing flux employed is preferably a lead borosilicate flux or "a bismuth compound, such as bismuth oiride-o'r'oxychloride.

If the paste is to be used to prepare a transfer, it will be found necessary to incorporate in {themedium a suitable plasticizeror plasticisers,

such'as methyl abietate and/or castor oil, in an amount equal to 50-200% of the weight of cellu- 4 lose derivative in the medium, for the purpose of preventing cracking of the decoration during transferring or firing.

A preferred composition of paste, formed in accordance with the invention and particularly suitable for preparing transfers for the decoration of glazed earthenware consists of the following:

Per cent by Weight Gold powder 26 Mercuric aurate 22 Low fusing lead b'orosilicate flux 1 YPIa'stici'Sed nitrocellulose medium, viscosity 200* 'cen-tisto'kes 51 .the 'said c'onstituents being ground together to form the paste.

fIh-is .paste, whilst being particularly suitable "for use in preparing atransfer by the silk-screen printing method for subsequent transfer to an article of pottery to be decorated, "may also be usedfor'direct silk-screen printing onitoa substantially fiat potteryarticle. I v

lfn the case of'the decoration of a-gla'ss article, it will-be found necessary to include a-hi'gh percentage (preferably 3%") "of flux in the paste owing to the lower firing'temperaturesemployed.

The preferred composition of the individual constituentsof the, improved paste is as follows:

Flux or adhesion pro matingconstituent Although any known 'lead *borosilicate flux which melts at-a temperature-or 400:500 C. or a bismuth compound may be used, we have 'found that the most satisfactory resultsare'obtained by using-a flux having the following-composition:

- er centby'weight Lead monoxidenen'n llri so BO I 'iCQXidB Silica 7 I Per cent'by' weight Gold sApproximately 55 Mercury r Approximat'ely 33 Water and oxygen Approximately 12 The mercuric aurate maybe prepared by adding'an aqueous solution of agoldhalide e. g.the chloride, to an aqueous solution of a mercuric salt other than a halidein amounts to give the required proportions, both solutions being at or near their boiling points, filtering and washing the precipitated mercuric 'aurate and drying at atemperature' below C.

In' the case where a'thinner depo'sit'isdesired, than will be obtainable With'th'e above com osition, l-'l0% (preferably 5%) by Weight of anthracene may be included in the paste, the

exact amount depending on the particularjefiect desired.

g In the useo'f the improved-paste 'fo'rth'e decoration, for example, of a-substaritiall-y flat article ofglazed earthenware, thepaste is applied to the article, so as to form an'y-desired design thereon, by the silk-screen printing method, and allowed to dry. The coated article is then fired ata-teinperature within the range of 700-750 Cite burn away the organic matter and cause the metallic gold to adhere firmly to the article.

If the base being decorated is of glass, the firing temperature should preferably be between 500 C. and 650 C., the exact temperature depending on the particular variety of glass under treatment.

The decoration, after firing, will present a matt surface, and may, if desired, be lightly scoured with sand or burnished with agate so as to produce a bright effect. 1 1

When the paste is to be used for preparing a gold'transfer, the paste is applied, in any desired design, to a sheet of transfer paper by the silk-screen printing method and is again allowed to dry. To decorate an article, the transfer paper, with the design thereon, is applied to the article and the design transferred to the surface thereof by the well-known slide off method. The article is then fired at a suitable temperature, i. e. within the range of 500-650 C. in the case of a glass article and 650-800 C. in the case of pottery or earthenware.

The fired design may, in this case also, be lightly burnished.

What we claim is:

l. A silk-screen printing paste for use in the preparation of gold transfer or for direct application to an earthenware base, said paste comprising a mixture of the following constituents in the following proportions by weight, namely:

Per cent Gold powder 26 Mercuric aurate 22 Lead borosilicate flux 1 Solution of plasticised nitrocellulose medium" 51 2. A gold silk-screen printing paste comprising a mixture of (l) mercuric aurate, (2) gold powder, (3) a flux chosen from the group consisting of lead borosilicate fluxes having a melting point no higher than 500 C., bismuth oxide and bismuth oxychloride and i) a liquid vehicle comprising a solution of nitrocellulose; the mercuric aurate, gold powder and flux being present in the following proportions of the total solids, namely: mercuric aurate-50% by weight, gold powder 50-90% by weight and flux l-l5% by Weight and the liquid vehicle being present in an amount to form with the solids a paste suitable for silk-screen printing, said gold powder, mercuric aurate and flux being always present and constituting together not more than 100% of the total solids.

3. A gold silk-screen printing paste comprising a mixture of (1) mercuric aurate, (2) gold powder, (3) a fiux chosen from the group consisting of lead borosilicate fluxes having a melting point no higher than 500 0., bismuth oxide and bismuth oxychloride and (4) a liquid vehicle comprising a solution of nitrocellulose; the mercuric aurate, gold powder and flux being present in the following proportions of the total solids, namely: mercuric aurate 10-50% by weight, gold P wder 50-90% by weight and flux l-% by weight; and from a trace up to determined on the weight of gold in the paste, of silver powder and the liquid vehicle being present in an amount to form with the solids a paste suitable for silk-screen printing, said gold powder, silver powder, mercuric aurate and flux constituting together not more than 100% of the total solids.

4. A silk-screen printing paste for use in the preparation of a gold transfer or for direct application to aheat-resisting base, said paste consisting essentially of a mixture of (1) gold powder, (2) mercuric aurate, (3) a flux selected from the group consisting of lead borosilicate fluxes having a melting point no greater than 500 C., bismuth oxide and bismuth oxychloride and (4) a liquid vehicle comprising a solution of nitrocellulose; the gold powder, mercuric aurate and flux being present in the following proportions of the total solids, namely: gold powder 50-90% by weight, mercuric aurate 10-50% by weight and flux 1-15% by weight; and from a trace up to 20%, determined on the weight of gold in the paste, of silver carbonate for the purpose specified and the liquid vehicle being present in an amount to form with the solids a paste suitable for silk-screen printing, said gold powder, silver carbonate, mercuric aurate and flux constituting together not more than 100% of the total solids.

5. A silk-screen printing paste for use in the preparation of a gold transfer or for direct application to a heat-resisting base, said paste consisting esssentially of a mixture of (1) gold powder, (2) mercuric aurate, (3) a flux consisting of by weight of lead monoxide, 13% by weight of boric oxide and 7% of silica and l) a liquid vehicle consisting of 56% by weight of amyl lactate, 20% of ethyl lactate, 8% of nitrocellulose, 8% castor oil and 8% methyl abietate, the mercul'lc aurate, gold powder and flux being present in the following proportions of thetotal solids, namely, mercuric aurate 10-50% by weight, gold powder 50-90% by weight and flux 1-15% by weight and the liquid vehicle being present in an amount to form with the solids a paste suitable for silk-screen printing, said gold powder. mercuric aurate and flux being always present and constituting together not more than of the total solids.

6. A silk-screen printing paste for use in the preparation of a gold transfer or for direct application to a heat-resisting base, said paste consisting essentially of a mixture of (1) gold powder,

(2) mercuric aurate, (3) a lead borosilicate flux and (4) a liquid vehicle consisting of nitrocellulose dissolved in a mixture of amyl lactate and ethyl lactate, the mercuric aurate, gold powder and flux being present in the following proportions of the total solids, namely, mercuric aurate 10-50% by weight, gold powder 50-90% by weight and flux 1-15% by Weight and the liquid vehicle being present in an amount to form with the solids a paste suitable for silk-screen printing, said gold powder, mercuric aurate and fiux being always present and constituting together not more than 100% of the total solids.

7. A gold silk-screen printing paste consisting essentially of a mixture of (1) mercuric aurate, (2) gold powder, (3) a flux chosen from the group consisting of lead borosilicate fluxes having a melting point no higher than 500 0., bismuth oxide and bismuth oxychloride, and (4) a liquid vehicle comprising a solution of nitrocellulose, said liquid vehicle also containing a small amount of a plasticiser selected from the group consisting of methyl abietate, castor oil and mixtures thereof and the mercuric aurate, gold powder and flux being present in the following proportions of the total solids, namely, mercuric aurate 10-50% by weight, gold powder 50-90% by weight and flux l-15% by weight, and together constituting not more than 100% of the total solids, and the liquid vehicle being present in an amount to form with the solids a paste suitable for silkscreen printing.

8. A goldtsilkescreennrinting paste consisting essentially of amixture of (1) mercuric aurate,

(.2) gold powder, (3) a lead'borosilicate fluxhav- :ingamelting point no higher than 500 C. and

tions'of the total solids, namely, mercuric aurate 10-'50% by-weight, gold powder 50-90% by weight and flux 145% "by-weight and constituting togethernot more than 100% of the total solids and the'liquid vehicle being present in an amount to :form with the solids a paste suitable for silk- .screen printing.

FRANK ENOCI-I KERRIDGE. "CYRIL STANLEY COUPER.

I REFERENCES CITED The following references are-of record in the file of'this patent:

UNITED STATES PATENTS Number Name Date 494,526 Forster Mar. 28,1893 682,310 Zsigmondy Sept. :10, .1901 982,370 Kurz Jan. 24', 1911 1,899,420 Lawrence Feb. 28, 1933 2,059,310 Bogin Nov. 3, 1936 2,103,598 'Smith Dec.:28, 1937 2,190,210 Kaber Feb. 13, 1940 2,318,803

Schneider etzal Mayll, 1943 

1. A SILK-SCREEN PRINTING PASTE FOR USE IN THE PREPARATION OF GOLD TRANSFER OR FOR DIRECT APPLICATION TO AN EARTHENWARE BASE, SAID PASTE COMPRISING A MIXTURE OF THE FOLLOWING CONSTITUENTS IN THE FOLLOWING PROPORTIONS BY WEIGHT, NAMELY: 